National Television Systems Committee (NTSC) was created in 1940 to provide a standardized format for television broadcast in the United States. The NTSC approved a 525 lines-per-field, 60 interlaced fields per second, with 4-3 aspect ratio using a 6-MHz bandwidth allocated per channel for transmission. The sound was frequency modulated and each channel was broadcast using vestigial sideband technique. In 1950, the committee was reconstituted to provide a standardized format for color television in the United States. The NTSC updated the earlier television standard to make it fully backwards compatible with the black-and-white television broadcasts.
In 1982, the Advanced Television Systems Committee (ATSC) was established to set broadcasting standards for digital television (DTV) broadcasting for the United States. The ATSC standard uses the same 6 MHz bandwidth allocated per channel for NTSC analog broadcasts. However, a television station can broadcast a plurality of different image sizes including a high-definition (HD) television program in 16×9 aspect ratio, a HD program in standard 4×3 aspect ratio, or standard definition (SD) program of the NTSC standard. Since a HD program in 16×9 aspect ratio has more than six times the pixel resolution of a SD program, a broadcasting station can mix the types of programs it will broadcast simultaneously in its allocated 6 MHz bandwidth. For example, a single HD program in 16×9 aspect ratio can be broadcast, or up to six SD programs can be broadcast simultaneously.
To transmit data more efficiently, ATSC chose the eight level vestigial sideband (8-VSB) modulation technique for broadcasting. ATSC uses MPEG-2 compression system to encapsulate data into 188-byte packets for transmission. However, 8-VSB's shortcoming is that it cannot be adapted to changes in radio propagation conditions, as might be found for mobile receivers. In order to take this into account, ATSC has since improved the transmission standard with addition of the optional, more robust transmission capability called the enhanced 8-VSB (E-VSB). E-VSB, while backwards compatible with the original 8-VSB, comprises an added layer of forward error correction to improve accuracy of received signals. While E-VSB enhances transmission and reception of HD television (HDTV) signals, there may still be problems in detailed implementations relating to powering-up or initialization of the E-VSB transmitter as well as synchronization of the E-VSB receiver to the transmitted data.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.